Rod type antenna



May 12, 1959 c. c. WILLIAMS ROD TYPE ANTENNA Filed Dec. 24:,v 1956 IN VEN TOR.

` Cha r//e C. W/'/ia/ns BY United States l hice ROD TYPE ANTENNA Charlie C. Wiiliams, Birmingham, Ala.

vApplication December 24, 1956, Serial No. 630,271

2 Claims. (Cl. 343-900) rl`his invention relates to an antenna and more partie ularly to an antenna which shall be especially adapted for use with portable radio receivers and transmitters.

An object of my invention is to provide an antenna of the character designated which will not break easily from vibration and bending, thus assuring that the radio set is in operating condition at all times.

Another object of my invention is to provide au antenna of the character designated in which there is a better impedance match between the antenna and the radio set due to the fact that the transmission line effect is reduced to a minimum.

A further object of my invention is to provide an antenna of the character designated in which there is less reilected power lost.

A still further object of my invention is to provide an antenna of the character designated which shall ,be simple of construction, economical of manufacture and one which is adapted for use on conventional type portable and mobile radio sets.

Heretofore in the art to which my invention relates, various types of antennas have been proposed for portable radio sets, such as by providing a relatively rigid insulating material around the antenna which is reinforced by a `metallic; sleeve. The metallic sleeve telescopes within an outer connecting sleeve member. members have been securd to the base of the antenna to prevent easy bending thereof. However, with such coil springs, the antenna still breaks at the same point that the antenna would break were the coil springs not placed around rthe same. Also, the coil springs and metallic sleeve members greatly increase the transmission line eitect. As is well known, where a metallic member extends over an antenna wire that portion of the antenna wire serves as a transmission line rather than an antenna.

l overcome the above and other diiculties by providing an outwardly tapered resilient member which surrounds the antenna rod adjacent the base end thereof. The resilient member is formed of a suitable flexible, dielectric, material, such as flexible rubber and like materials which are substantially free of carbon.

By providing the outwardly tapered resilient member adjacent the base of the antenna rod, the inner sleeve heretofore employed is eliminated and the antenna rod may be connected to the usual coaxial connection on portable radio sets by a relatively short sleeve member, the portion of the sleeve member extending over the resilient member being approximately one-quarter inch. Furthermore, by providing the sleeve member of a suitable dielectric material, the transmission line eiect is eliminated and a substantially perfect impedance match can be obtained. The tapered resilient member not only provides a better impedance match between the antenna and the set but also prevents the antenna rod from being bent sharply at a particular point. That is, when the free end of the antenna rod is moved relatively to the base end thereof, the rod bends in a uniform arc.

Antennas embodying features of my invention are illus- Also, coil spring 2 trated in the accompanying drawing forming a part of this application, in-which:

Fig. 1 is an enlarged vertical section view, partly broken away;

Fig. 2 is an enlarged vertical section view, partly broken away, showing a modied form of antenna; and

Fig. 3 is an end elevational View taken `generally along the line llI--III of Fig. 2.

Referring now to the drawing 'for a better understanding of my invention, I show the usual coaxial connection for portable radio sets, and the like, which comprises an outer cylindrical member 10 having a concentric tubular member which forms a centrally disposed socket 11. A suitable insulating material 12 is provided between the cylindrical member 10 and the socket 11, as shown in Fig. 1.

The antenna rod indicated generally at 13 is provided with the usual contact 14 at the base end thereof. Surrounding the antenna rod 13 adjacent the base end there- `of is an outwardly tapered resilient member 16 which is formed of a suitable dielectric material, such as flexible carbon free natural rubber or the like. In actual practice, i have found that rubber compounds which meet A.S.T standard R620 and military classification mill-R.6855 class l are satisfactory in every respect. The `resilient member is preferably annular as viewed in transverse cross section. The inner end of the resilient `member 16 isenlarged in diameter as `at 17 and is provided with an annular shoulder 18 at `the outer end of the enlarged diameter portion. Telescoping over the enlarged diameter portion 17 of the resilient member 16 is a sleeve connector 19 having an annular inturned flange 21 adjacent the outer end thereof adapted to engage the annular shoulder 18 whereby the `resilient member -16 is held against outward movement relative to the sleeve connector 19. The sleeve connector 19 may be formed of a metallic material. However, by formingit of a dielectric material the transmissionline effect is eliminated.

To prevent `lateral shifting ofthe inner or base `end of theantenna `rod 13` relative to the resilient member 16, I provide a relative rigid disc member 22 between the contact 14 and the inner surface of the resilient member 16. The disc member 22 is also formed of a suitable dielectric material. The diameter of the disc member 22 is equal substantially the internal diameter of the sleeve connector 19. The sleeve connector 19 is provided with internal threads 23 adjacent the inner end thereof which are adapted to engage suitable threads 24 formed on the cylindrical member 10 of the radio set. As shown in Fig. l, the contact 14 enters the socket 11 when the antenna is connected to the radio set.

Referring now to Figs. 2 and 3 of the drawing I show a slightly modified form of antenna comprising an antenna rod 13a having a contact 14a adjacent the inner or base end thereof. Surrounding the antenna rod 13a adjacent the base end thereof is a resilient member 16a which is also preferably annular as viewed in cross section and is formed of a suitable dielectric material, such as the flexible rubber described heretofore. The resilient member 16a is provided with an enlarged diameter portion 17a having an annular shoulder 18a adjacent the outer end thereof which is adapted to receive an inturned annular flange 21a formed at the outer end of a sleeve connector 19a which is similar in all respects to the sleeve connector 19. The resilient member 16a is provided with a plurality of axially extending sections 26, 27 and 28 which are progressively smaller in diameter toward the outer end of the resilient member 16a, thus providing a generally outwardly tapered surface for the resilient member. A relatively stiff disc member 22a formed of a suitable dielectric material is positioned between the contact 14a Y 3 and the inner end of the resilient member 16a to limit lateral shifting of the base end of the antnna rod relative to the sleeve connector 19a.

Secured to the free end of the antenna rod 13a is a `disc member 29 which serves `asa safety member to prevent damage tothe eyes of the operator when the antenna is used on portable and other type radio sets. The disc member 29 is attached to the antenna rod 13a by any suitable means, such as by providing an outturned annular ange 30 adjacent the central portion of the disc member for receiving the looped-shape end 31 of the antenna rod 13a, as shown in Fig. 2.

From the foregoing, it will be seen that I have de vised an improved antenna which is particularly adapted Vfor use with portable or mobile radio sets. l By providing the outwardly tapered resilient member adjacent the base of the antenna rod, the rod is not'easily bent, thereby assuring that the antenna remains in operating condition at all times. This is especially desirable in View of the fact that with certain uses, the loss of the of the use of the radio set even for a relatively short period of time causes great inconveniences and expense. For instance, when used by railroad men in the switching of trains, hand signa-ls are wholly ineffective due to the length of present day trains. This is especially true when the train is positioned on a curve. It will thus be seen that with the portable radio set out of operation, not only would the train directly concerned be inconvenienced and delayed, but the schedule of other trains would also be inconvenienced.

Also, by providing a dielectric resilient member around the base of the antenna rod, the length of a metallic sleeve connector may be reduced to a minimum, thereby reducing the transmission effect of the connection between the antenna and the radio set. Furthermore, by providing a dielectric sleeve connector which surrounds the enlarged diameter base end of the resilient member, the transmission effect in the antenna is eliminated whereby a substantially perfect'impedance match is obtained between the antenna and the radio set. Furthermore, by providing the outwardly tapered resilient member, a better impedance match is obtained. Not only is the inner metallic sleeve heretofore employed eliminated entirely, but in actual practice I have found that the tapered shape 4 actually provides a better impedance match than a resilient member having an abrupt end.

While l have shown my invention in but two forms it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

l. The combination with a radio having a coaxial connection embodying a cylindrical member witha c ontact receiving socket disposed inwardly thereof, of an antenna rod having a contact at its base and disposed to engage the socket of a coaxial connection, an elongated, outwardly tapered, dielectric, resilient member surrounding said antenna rod adjacent the base end thereof with said contact at the base end of the yantenna rod projecting outwardly thereof, a sleeve-like member telescoping over the inner end of said resilient member with the entire inner surface of said sleeve-like member which is opposite said resilient member beino in direct contact with said resilient member, a relatively stiff, dielectric disc member surrounding the antenna rod and in direct contact with the inner end of the resilient member, the outer diameter of said disc member being equal substantially to the internal diameter of Asaid sleeve-like member whereby said disc member is disposed to contact the outer end of the contact receiving socket, and means for attaching said sleeve-like member to the cylindrioal member of a coaxial connection.

2. An antenna as defined in claim l in which the sleeve-like member is also of a dielectric material.

l References Cited in the le of this patent Zaun and Callaghan, abstraction of application Serial Number 64,582, published January 8, 1952 (654 O.G` 632). 

